When you make a new topic, please choose a “category” for it using the popup to the right of the topic title.
The way I set up the site, the Orientation category is public (requires no login) and is supposed to be for outward facing stuff, like describing reasonably-settled Push language features or lexicase selection algorithms, etc. Other stuff should have a non-Orientation category, which will mean that only people with logins can see it. The idea is that this allows us to talk about work in progress, etc., without the entire world watching.
The rub is that, the way I set it up (and I’m not sure if/how I can change this) topics with no specified category are also public. When I see those, I add a category myself, but ideally everyone would post with a category in the first place.
The existing categories are not perfect, and sometimes it’s hard to know exactly what category to use. But I think they’re close enough, and it’s not a big problem to use a less-than-ideal category.